A technology for treating the human body using a method of modifying the state of a human tissue or removing a specific tissue using a laser has been widely applied. A treatment apparatus for treating a variety of types of human body tissues including the skin has been actively developed using various light sources, such as a laser source, a flash lamp and an LED.
A laser apparatus outputs a laser beam having monochromatic, coherence and collimation. The laser beam output by the laser apparatus is output with energy having a different wavelength or different pulse width depending on a change in the oscillating condition of the laser beam. In general, a laser treatment apparatus that is now commercially sold outputs a laser having a pulse width of a micro-second band. For precise treatment, there is a need for the commercialization of a laser having a nano-second pulse width, but it is difficult to commercialize a laser depending on the type or wavelength of a laser medium. In particular, Er:YAG is widely used as a medical laser medium, but had a difficulty in generating a laser having a nano-second pulse width due to medium characteristics.